Field of the Invention
The present invention relates to a charging member, a process cartridge, and an electrophotographic image forming apparatus.
Description of the Related Art
In an image forming apparatus using an electrophotographic method, a charging member allows an electrophotographic photosensitive member (hereinafter also referred to as “photosensitive member”) to be charged to a predetermined potential. The charging member usually includes an elastic body such as rubber or elastomer of which surface is provided with a surface layer of, for example, cross-linked urethane. A conducting agent is dispersed in the surface layer so as to impart conductivity.
Due to electric energy intermittently applied to the charging member in an electrophotographic image forming apparatus (hereinafter also referred to as “electrophotographic apparatus”), the electric resistance of the charging member gradually changes, causing uneven charging and charging defects, which result in image defects in some cases.
In Japanese Patent Application Laid-Open No. H03-9380, a technique for suppressing the occurrence of charging defects by addition of a hindered phenol material to the surface layer for suppression of deterioration of the surface layer material is disclosed.